Project Summary/Abstract The Healthy People 2020 goals prioritize reduction of the cesarean rate by 10% for low-risk women. Labor dystocia accounts for almost 50% of cesarean deliveries (CD) in the United States (MICH-07.1). The American College of Obstetricians and Gynecologists and the Society for Maternal and Fetal Medicine identified accurate diagnosis of labor dystocia and the judicious use of CD for this indication as an opportunity to reduce the overall CD rate.1 In the United States, nearly half of all labors are augmented using Pitocin; however this augmentation has not been found to reduce the risk for CD. Moreover, some women with labor dystocia do not respond to Pitocin. The applicant seeks to contribute to understanding the pathophysiology of labor dystocia to find novel approaches to reducing the unnecessary use of Pitocin augmentation and CD. Elevated amniotic fluid lactate (AFL) and increased median Power Density Spectrum (PDS) frequency, a measure of the electrical activity of the uterine muscle during labor, recently were found to be associated with labor dystocia and CD. AFL and median PDS frequency monitoring have been proposed separately as tools for identifying women at risk for arrest of labor and CD. The proposed research will characterize labor dystocia phenotypes by AFL concentrations and median PDS frequency to improve diagnostic precision labor dystocia. Improving diagnostic precision for dystocia will allow for individualized management that reduces unnecessary CD and optimizes fetal and maternal outcomes. The applicant has synthesized research findings to classify labor dystocia by rate of cervical dilation graphed on a partograph, then by adequacy of uterine contractions, and AFL. The proposed research will contribute to a better understanding of the pathophysiology of labor dystocia to generate future research hypotheses that contribute to the development of the proposed phenotypic classification of labor dystocia. In addition, the proposed research will evaluate the correlation between point- of-care capillary lactate collected by maternal finger stick and AFL. Evaluation of AFL is limited as it can only be collected non-invasively following ruptured membranes. If point-of-care capillary lactate is predictably correlated with AFL, it may be used as an alternative biomarker beginning in early labor to identify abnormal labor patterns, from which an appropriate management plan is determined. Instead of uniform use of Pitocin augmentation, innovative interventions that rest and restore uterine contraction may be indicated, including tocolytics, dextrose, or sodium bicarbonate.